Dead bolt latch



l. J. FLETCHER DEAD BOLT LATCH' Oct. 20, 1953 Filed Aug. ll, 1949 jiyJJ. 15K-.152

dw c a; 3M 3M" 0 43 M Q G o 38a o sa@ v 2 Sheets-Sheet 2 Patented Oct. 20, 1953 UNITEo rsf'rATES 'DEAD *BOLT LATCH Irving J. Fletcher, New Britain, Conn., assignor to The .American Hardware Corporation, New 'ritaim Conn., a corporation of Connecticut ApplicationA Augustxn, 19.49., ,serial N0..:1o9,cs.s

'15 Claims.

VTlhis'im/.ention.relatesto azdead bolt latchand l more particularly to a latch :in Iwhich fthe latch- -fm'g bolt., when `in latchnsrposition,.automatically becomes inoperative so that it may not be moved `Tinto `lunlatched position vexcept by operation of 5 fthe operating member which is provided therefor,

It is Well known 'to f'zthose skilled in the art `that dead bolt latches commonly contain a A'latchingboltfandzaseparateauxiliary bol-t `which 10 operates-a .mechanism `for rendering the latching j:bolt immovable after it has 'moved into latchsing position. Such latches, however, have been qcormolicated 1in construction and, therefore, ex- 15 for, and which 'becomes Aloper-.able `independently 20 toi said noperating member upon being rotated by engagement Awith a :cooperating strike-r eplate that:is'associated with a vdoor on lwhich vthe said latch is used.

.A :further object of this invention is to provide la l-atch ainwhichthe latching bolt thereof becomes r'immovable, "when `the same sis in latch- -ing position, so that it may not -be forced back rinto unlocked position --by manipulation of the `holt `fromtheexterior-of the latch.

3o A further objectis the provision of sui-tables.;

:and eleetive means @for preventing rotation of thelatchi-ng loolt, when in latching position .so that it may not ybe forced back vinto `unlatched UGS'of-l. l 3 5 iafstill @fart-her lobjectof this invention -1s tog.; provide '5a v.dead holt lock f'having novel ieatures not heretofore providedlinsuch .locksand which is durable in construction and may fbe reconom- "finally manufactured. 4 0

Further objects and advantages `ol this finyreaction :Wil-libe more 1clearly understood from I.the 'foll'owing description and `the accompanying drawings which: Y

fil :is @a plan View `of -my amprov-ed latch 45 isffa rear-view of the said latch partly `in central V:vertical section.

lf`r-ig--4is anfexteriorend view .of the latch and a portion pf vthe door .to which ritfis attached.

thregiatch in aretracted orunlatohed position.

Fig. .6 is :a .sectional .end view on -line B- .of Fig. l.

:Fig 7 :is a sectional end view online T-l of Fig. 5.

Eig. 8 ,is .aplan r4view,partly .in section, show- .ing ithe operation .otmy improved latch as it `is moved towards `latching position.

Fig. -9 -is an end view thereof on line 9-5 of Fig. .8.

Fig. l0 lis a plan View. `similar tor Fig. 8, but

sho-wing -thediierent position .during .the operationfof the latch.

Fig. 1.1 .is `a reduced diagrammatic .end view or `the striker plate andlatching ,bolt in the relative position .illustrated .in Fig.

Fig. l2 .is ua similar View with lthe parts in .the

relative position illustrated vin Fig. V.1.0.

Fig. r.13 4is a reduced diagrammatic end yView `showing a modied .form vof .striker plate .and

latchi-ng holt.

Eig. l-Ltis asimilar view `showing the llatching holt in .a dierent position.

In .thepreferred `form .illustrated in .the drawings, my improved latch comprises ,a tubular cas- ,.-ing 5 which .has -securedtheretoa .fasteninsplate Aincludingfa main plate .thatis secured .to the exterior Kof the casing, .at the end thereof1 and :anrauxiliaryplate l `which is secured .to .theplate t .and extends over .the endof the -casinlg` for the purpose hereinafter described.

.The mechanism .of -my improved latch comprises a .latching bolt having ,a head portion 8 which is slidable in the .tubular `casing .15. A stem #l extends fromlsaid head `portion .through a backing .plate l!) that is disposed within vthe said .casing .andpositioned therein by means of `posts 11.-!! which extend from .a vsupporting .block consisting of .two opposed halves lil-I2 that are secured to the casing 5 by means of a positioning pin I3.

The said. v'backing plate I is secured Vto the posts 'l l-H b y means'of notches M which receive reduced portions within grooves I5 Iin each of said posts.

'A combined compression and torsion'latching bolt spring 'member IIB :is provided between the 'head portion Aand the `backing plate Il) for normally urging the vsaid `l'atching bolt in an foutward'di-rection from the casing and into its latchingposition; thersaid spring fbeing vsecured against :rotation Tela-tively =to the backing plate ltl by means of a hooked end portion .ifi .and relatively to the latchingbolt hy means of an inwardly projecting endportion !8 which ex tends vinto a hole :in the Vshank 3. Y

l A pair lof opposed 'bolt :operating vyokes :lt-:I9

...o are slidably mounted upon the posts il-H and each of said yokes has a pair of opposed operating bars Eil- 20 which are spaced apart and extend rearwardly therefrom. The said operating bars are each provided at their inner ends with laterally extending hook portions 2| which engage opposite sides of a pair of roll backs 22-22, each of which is secured to the adjacent end portions of an operating spindle which extends from opposite sides of the door and may be formed of two separate sections 23-23 to permit rotation of one portion of the spindle independently of the other; each of said sections being provided with a conventional operating knob.

On each of the posts lI-H there is provided a compression spring 24 which is disposed between the block formed by the halves |2--I2 and one of the yoke members i9 and urges the said members into their normal position wherein the latching bolt is permitted to be moved into latching position under the tension of the spring member i6.

A pair of blocking levers 25-25 are pivotally mounted at 26-26, between opposed inwardly extending portions on the block halves I2-|2, and extend forwardly from said pivotal points with their free ends 25-b-25-b providing obstructions normally in the path of movement of radial projections 21-21 which form detents on the latching bolt stem 9. Each of said levers 25-25 has an extension ZS-a with a cam portion thereon that is engaged by a spreader roller 23 mounted between the related pair of opposed operative bars 2li-20. The said levers are urged towards normal position and into engagement with the said rolls by means of a spring member 29 having leg portions fitting into notches in the said levers, as shown, for urging the extensions ZB-a outwardly and thereby normally retaining the free ends 2547-25-73 of the levers 25-25 in the path of the radial projections 21H21 on the shank 9.

The fastening plate portion l is provided with an irregular opening having a circular portion m ,ma an ihwqra'lv projecting .st/o portion. ii which engages a attened surface 32 on the ba ck of the bolt. to limit rotation. of the bolt under the influence of the spring member I6. and overlies a stop shoulder 33. formed bv said flattened surface inwardly of the circumferential surface of the portion. 3d on the head of said bolt t0 limit movement of the bolt towards latching po sition also under the influence of the said spring member. The front portion of the said bolt is provided with a bevelled cam surface 35 that is attened on an angle to the longitudinal axis of the bolt and to the normallv vertical plane passing through the axis thereof so as to Drovide a cam surface for both rotating the bolt and forainer it rearwardlv towards retracted position as will be hereinafter described.

In the preferred form illustrated, my lock is used in combination with a striker plate 3S which is secured to the frame 31 of the door and has a portion 38 extending therefrom and curved backwardly from the door, as indicated at 39, to cooperate with the cam surface 35 of the locking bolt for retracting it as illustrated in Fig. 8.

IIhe said striker plate is provided with a hole 4i! having a straight edge portion 4| which engages the flat surface 32 of the latching bolt,

when the said latching bolt is in latching posij tion Within the said hole 4G, and prevents rotation thereof.

In the modified form illustrated in Figs. 13 and 14, the disposition of the cam surface 35 on an angle to the said normally vertical plane is omitted and, instead, the said surface is made at an angle only to the axis of the bolt and parallel to the said normally vertical plane, as shown at SE-a, and the projection 38-a of the striker plate 3l-a extends outwardly and backwardly therefrom on an angle to the vertical axis of the bolt.

`Such locks of the type herein described are commonly provided with key operated means for preventing operation of the spindle 23 for drawing the latching bolt back into unlocked position. Such key operated means may be of conventional form and may operate to lock the said spindle 23 in any suitable manner well known to those skilled in the art and are not, therefore, shown in the drawings.

The operation of my improved lock is as follows:

When the latch is in the latched position, as illustrated in Fig. 3, the latching bolt 8 projects through the opening 4l! in the striker plate B and locks the door in closed position.

Assuming that the spindle 23 is locked by the key operated means; the latching bolt cannot be withdrawn into the casing 5 so as to unlock the door. Upon the said key controlled means being operated to release the spindle 23, the said spindle may be rotated in either direction whereupon one of the roll back members 22 will engage the projections 2l on a pair of the yoke bars 2S and thereby draw rearwardly an operating yoke I9 which is connected to the locking bolt by means of the projections 21--2'L This will cause the spreader rollers 28 to operate the levers 25--25 and thereby spread them, to the position shown in Fig. 5, wherein the obstructing ends thereof will be out of the path of the projections 21-2'! and thereby permit the said yoke member I5 to withdraw the bolt into unlatched position, as illustrated in Fig. 5. It will therefore be understood that, when the lock is operated by the rotation of the spindle 23, the levers 25-25 are spread apart, against the tension of the spring 29, so as to permit the bolt to be drawn back into retracted position.

When the door is to be moved from an open to a closed position, it is required that the latching bolt 8 be retracted into the casing 5 to permit the door to close. This is permitted by the latching bolt being first rotated so that the projections 21-21 on the bolt will avoid the obstructing ends of the levers 25-2 5.

The bolt is rotated upon engagement of the angularlydisposed cam surface 35 thereof with the backwardly curved portion 39 of the striker plate, as illustrated in Figs. 8, 11 and 12. When `the said cam surface strikes the end of the curved portion 39, the bolt will be rotated, from the position shown in Fig. 11 to that shown in Fig. 12, so that the said projections will be in the position shown in Fig. 9 and out of alignment with the ends of the levers 25-25.

As the door continues to move towards close-'l position, the bolt will be forced inwardly by means of the angle in the surface 35. This will cause the spring t5 to become compressed and, at the same time, torsioned by the rotation of the bolt until the said bolt reaches the position illustrated in Fig. 10. In this position. the bolt will be in contact with the surface of the striker 4plaie i 3B -xmly 'the hgh point fiindcate'd A2 which .is formed by :tapering the endfsnrf-ace :of the 'fbolt :outwardly :and downwardly from tithe 'longitudinal -axis f thereof :and 'which "will 'act Aas l'affulcrumto ithereby permit .rotationaofzthe bolt V.with a fminimum A.of ifriction .so that jtxwill .fbe quickly rotated :in a yrrenfersed direction, .abyzrthe unwinding i action of fthe spring 1.6, V:towards its .normal position illustrated .in `Fig. f4. When `this position, fthe bolt `Willkbe:positioned A:by means :of fthe :engagement between the flat surface .1.32 fand the'edgelof the projection 43| iin fthe hoieiin the auxiliary plate 1. thedoor vreaches :its 'fully closed zpos'ition, :the bolt'will ib'e 1in A"alignment lsvitl'i the opening du in .fthe striker jiplate 'I'.

P38 and :will tbe 'moved by .the @expansion of the spring it lso .that fit is :protected .outwardly :from thecasing'tvand'intosaidtopening.

During A.this `.movement `of :the 4latol'ns bolt, the `*pro iections 'FZ7- 21 will engage 'the cam :sur- 4-faces 2`5-a--25-a y.on the blocking levers Aand spread said .levers apart to permit .the said fproj ectons to `motie 'with the .bolt'cpast'the.obstruct- "mg portions vof thelevers.

iIt willbe noted that rthe *inward'movement zof 'thefbolt rcaused by the striker plate is .resisted only *by the spring 'member 1.6 .which is backed the plate Ill, and 'that no action :is applied 'against the springs T223 during such movement. permits Ia much desired easy :action on the bolt'ivhen it is retracted by engagementwththe striker lplate and not fiby the operation 1of the spindlelz.

"when the bolt :iis 'return-ed .into latching position within 'the @neming F40, the `rotation of :said

bolt "is prevented'ibyrenaaaementbetween the `flat surface `32 vand the strain-ht -surface ."41 at Athe 'side of the hole-'Soil This `.will prevent manipula tionofthe bolt by 1an unauthorized person, who may-attempt to rotate the bolt with an improfvise'd Stool, so 3as to force :it .back into nnlaftched position, since Athe bolt :cannot be xmoved back 'Without I being .Tir-st rotated because fthe projections 2:5-27 :would strike the obstrnctin'g?,r .fends :of `the blocking leversiZE--Z It will, therefore, be noted 'that "the bolt fof `my improved latch .cannot be moved 'to unlocking .position by ltarn- `pering .with the boit through the space between 'the door Vzand tlfiedoor .frame since `the Vsaid bolt cannot berotated While in latched position and, therefore, -cannot'be orced back into .unlatchfed position. This is anrimportant :elementof .my inrmention.

.It will .also fbenoted-tha't avery important `feature :is provided iin :my improved latch through the application of a light pressure by the 'spring :against the retractiondof :the :ilatching bolt by the striker :plate :and ,.a heavier `.pressure :against the operationfoi the 'zbolt'eby 'meanseoflthe knob spindles 2i- This feature cis lhigllliy .desired :in lock constructions .since ait permitsfooerationof fthe bolt .zby the striker ',plate, so that `the .door will be :permitted 'to close easily, and fa stiffer operation @of the .boit Eby :rotation :of 4the knob spindlegso that thesaid spindle will bewmore readily neturned to Litsnormalpnsitioniuponabeing released.

Alrorn the abone description, it 'will loe clearly .understood that I has/:e :provided :a :novel dead :bolt .latch in v"which vthe latcliing 4bolt 'cannot be fforced back .into nnlatched 'position ,Without:first .being rotated rand which cannot 4loe .so rotated .while fthe door is in closed position.

.-Iiclaim:

si. n fla-tch mechanism comprising a latchne latching position, imeans for preventing .move- -ment of said .iioolt itc an nnlatohed position, the sai-d fmeans being .operable upon :rotation of .the fb'ltto permitmovementthereof to an unlatched position, :and cooperating means onsaid plate vaand'{bolt-Fior"prei/'exitingrotation `of `the bolt when lin lathedposition.

Aflath mechanism including alatching'bolt, a striker-plate toreceve said bolt, means for prewventing :movement or the bolt to van .unlatched position, said fm'eans being .operable upon .rota- `tit-m `of ftheboit to permit movement thereof to an Imolatohed position, the said bolt having .'a "straight `surface thereon, and means on .said striker 'plate cooperating with said straight v'sur- Jfase-for 'preventing rotation ofthe bolt when in 'latch'ecl position.

A 'latch-mechanism including a 'latching bolt, means for preventing movement of the bolt into `unlatched position, the said means being operable `upon Vrotation of the bol-t `to permit movement thereof to ian unlatched position, a striker lplate for 'receiving said bolt, a cam surface on said 'bott -angularlydisposed'relatively to the vertical axis vthereof tor rotating the 'bolt upon engagement with the said strik-er plate, and a flat surtace on said bolt engageable with aicooperating portion of sai-d striker plate for preventing 1rotation -o the 'bolt rwhen in 'latched position.

4. 'ln v.a Ivlatolrl-ng mechanism, the combination of a casing, a Iatching bol-t normally projecting outwardly ffrom said cas-ing into latching position `and retractablethereinto, 4means for preventing Imovement oi said bolt to retracted po- .siti-fon; said means .being Aoperable upon `rotation of the bolt to permit movement thereof v-to its 1retracted position, and fa z-strikerplate `for receiving said boltwhen in latching position; the said 4bolt 'having a surface disposed for rotating Aand retracting :it upon engagement with the striker plate and a 4surface -engageable with a cooperat- :ing por-tionen said striker plate 'for preventing u "rotationof the fbolt'wlien in latched position.

"5. A latch mechanism including a casing, -a rotatable latchling boltnormally projecting from said cas-ing into "latching yposition and retractable `therein 'into unlatched position, a striker plate, movable bloc-king means in the path of the -bolt lfor preventing retraction thereof, cooperative meanson said striker plate and said boltffor rotatingthe bolt, the said blocking means permitting retraction of the bolt upon rotation thereof, manually operable means for retracting said-100113, 4said manually loperable means includ- Viff-rg a spindla-'aro'll'back'member on Vsaid spindle, a yoke operable by said rollback member, means connecting `said bolt -to said yoke for retraoting thebolt upon rotation of the spindle, and means Voperable upon movement of said yoke to move said blocking `means from Athe path of the `bolt andto .therebypermit retraction of the bolt,

6. A latch mechanism including a casing, a '.latching `bolt Anormally,projecting from said cas- .ing into '-,latching position and Vretractable .thereininto unlatched position, ,a detent on .the .end of said bolt, a blocking member in the lpath of .the boltiengaeeablewith said detent to prevent .r.etraction-oithelcolt, thesaid datent being movable :upon rotation of the bolt to avoid the said .blocking member and permit retraction of the bolt, manually operable means'for .retracting .the bolt, andmeans operable upon the operation ,of the manually operable .means for .moving said blocking member out of the path of the detent to permit retraction of the bolt.

'i'. A latch mechanism including a casing, a latching bolt normally projecting from said casing into latching position and retractable therein into unlatched position, a detent on said bolt, a blocking member having an obstructing portion engageable With said detent to prevent retraction of the bolt, means for rotating the bolt to cause said detent to avoid the obstructing portion and permit retraction of the bolt, means for retracting the bolt upon the rotation thereof, manually operable means for retracting the bolt independently oi the first-mentioned retracting means, means operable upon the operation of the manually operable means for moving the said obstructing portion out 4oi the path of the detent to permit retraction of the bolt, and separate means operable to remove the said obstructing portion from the path of said detent and thereby permit the return of the bolt to latching position.

8. A latch comprising a casing, a 'bolt slidable in said casing into latching and retracted posi- 'projecting from said stem, a blocking lever pivotally mounted in said casing and having an obstructing portion normally positioned in the path of said detent to prevent retraction of the bolt, a spring urging said lever into normal position, a manually operable member, means actuated upon the operation of said member including an operating yoke for drawing the bolt into retracted position, and means movable with said yoke for rocking the lever against the tension of said spring to move the said obstructing portion out of the path of the detent and thereby permit retraction of the bolt.

9. A latch comprising a casing, a latching bolt normally projecting from said casing into latching position and retractable therein into unlatched position, a fastening plate connected to the end of `said casing and having an opening therein through which the bolt projects, stop means on the bolt eng-ageable with said plate to position the bolt in latching position, means requiring rotation of the bolt to permit retraction thereof into unlatched position, means for rotating the bolt in one direction to permit retraction thereof, a spring member for rotating the bolt in an opposite direction to return it towards i able in said casing into latching and retracted positions, means for preventing retraction of said bolt, the said means being operable upon rotation of the bolt to permit retraction thereof, a spring member yieldingly urging said bolt into latching position, a striker plate having an opening therein to receive said bolt when in latching position, cooperating means on said bolt and striker plate for rotating the 'bolt and then retracting it, and a high point upon the end of said bolt engageable with the surface of said plate to provide a turning point for minimizing friction in the rotation of the bolt toward latching position.

1l. A latch comprising a latching bolt normally extending from a casing in latching position, means 1 resiliently urging said bolt into latching position, a striker plate having an opening therein to receive said bolt when in latching position, means for preventing retraction of the bolt, said means being operable upon rotation of the bolt to permit retraction thereof, a spring yieldingly resisting retraction and rotation of the bolt, a cam surface on said bolt engageable with the striker plate for rotating and retracting the bolt against the tension of said spring, a flat surface on said bolt engageable with a corresponding portion of the w'all of the opening in the striker plate to prevent rotation of the bolt when in latching position, and a high point upon'the end of said bolt engageable with the surface of the strikel1 plate, after the bolt has been rotated in one direction and retracted, to minimize friction in the rotation of the bolt in the opposite direction and thereby permit the return of the bolt into latching 'position under'the tension of said spring.

l2. A latch comprising a casing, a bolt slidable in said casing and including a head portion and a stem portion, a fastening plate secured to an end of said casing and having an opening therein through' which the head of the bolt projects in latching position, means normally urging the said head into latching position, cooperating stop means on said bolt and plate for locating the bolt in said latching position, av backing plate having an opening therein slidably receiving the said stem, a spring member between said backing plate and head of the bolt rotatably and slidably urging the bolt towards latching position, projections on said stem portion, a pair of levers having abutment portions normally positioned for engagement with said projections to prevent retraction of the bolt, spring means for urging said levers to normally position said abutment portions, manually operable means including a rotatable spindle, a yoke engageable With said projections, a roll-back member on said spindle for operating said yoke for drawing said bolt into retracted position, cooperating cam means on said yoke and levers for separating the abutment portions against the tension of the spring means to thereby remove said portions from the path of the projections to permit retraction of the bolt upon the rotation of said spindle, spring means normally urging the yoke to cause return of the bolt to latching position under the tension of the said spring member, cooperating cam means on said bolt and striker plate for rotating the bolt and then retracting it independently of the said manually operable spindle, cooperating means in said bolt head and striker plate to prevent rotation of the bolt when in latching position, and a high point on said bolt engageable with the surface of said surface striker plate, after the retraction thereof, to minimize friction in the rotation of the bolt towards its normal position.

13. A latch comprising a casing, a fastening plate secured to the end of said casing and having an opening therein, a bolt slidable in said casing and having a head normally projecting through said opening, cooperating stop means on said plate and head for locating the bolt in latching position, a spring normally urging the bolt into said latching position, a stem projecting from said head, projections on said stem, a spring rotatably and slidably urging the bolt towards its latching position, a block secured to said casing, a pair of blocking levers pivoted on said block and having obstructing portions normally disposed in the path of movement of said projections to prevent retraction of the bolt, a spindle rotatable in said block, roll-back members on said spindle, a yoke operable by said members for drawing the bolt into retracted position, cam means on said levers, rollers on said yoke engageable with said cam means for rocking the levers to move the obstructing portions out of the path of the projections upon the rotation of the spindle and thereby permit retraction of the bolt, supporting posts extending from said block, a backing plate positioned by said posts, springs on said posts resiliently urging the yoke towards normal position to permit the return of the bolt to latching position under the tension of the first-mentioned spring member, a striker plate having an opening therein adapted to receive said bolt when in latching position, cooperating cam means on said bolt and striker plate for rotating said bolt to cause the said projections to avoid the said obstructing portions of the levers and then retract the said bolt against the tension of the spring member, a high point upon the end of said bolt head to minimize friction and permit rotation of the bolt towards latching position, and cooperating means on said striker plate and bolt to prevent rotation of the bolt when in latching position.

14. A latch comprising the mechanism set 10 forth in claim 13 and including cam means engageable by the projections to move the obstructing portions out of the path of said projections and permit the return of the latching bolt to its latching position.

151A latch mechanism comprising a latch bolt, means engageable with said bolt for pre venting depression thereof; the said means being adapted, upon rotation of the bolt, to permit depression thereof to unlatched position and means on the bolt and forming an integral part thereof for preventing rotation thereof when in latched position.

IRVING J. FLETCHER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 549,143 Link Nov. 5, 1895 1,900,328 Boggs Mar. 7, 1933 1,999,311 Voight Apr. 30, 1935 2,086,982 McCarter July 13, 1937 

